Add a spec to support namespaces in attr binding.

Attribute namespaces can be defined by `xmlns:<i>prefix</i>="namespace-url"`
attributes, and allow all descendents of that element to define
`<i>prefix</i>:name="value"` attributes.

spec/defaultBindings/attrBehaviors.js

@@ -9,6 +9,24 @@ describe('Binding: Attr', function() {
         expect(testNode.childNodes[0].getAttribute("second-attribute")).toEqual("true");
     });
 
+		it('Should be able to set namespaced attribute values', function() {
+				var model = { myValue: "first value" };
+				testNode.innerHTML = [
+					'<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink">',
+						'<g>',
+							'<a data-bind="attr: { \'xlink:href\': myValue }">',
+								'<text>foo</text>',
+							'</a>',
+						'</g>',
+					'</svg>'
+				].join('');
+
+        ko.applyBindings(model, testNode);
+				var anchor = testNode.childNodes[0]/*svg*/.childNodes[0]/*g*/.childNodes[0]/*a*/;
+				expect( anchor.getAttributeNode('xlink:href').value ).toEqual( 'first value' );
+				expect( anchor.getAttributeNode('xlink:href').namespaceURI ).toEqual( 'http://www.w3.org/1999/xlink' );
+		});
+
     it('Should be able to set \"name\" attribute, even on IE6-7', function() {
         var myValue = ko.observable("myName");
         testNode.innerHTML = "<input data-bind='attr: { name: myValue }' />";
@@ -62,4 +80,4 @@ describe('Binding: Attr', function() {
         expect(testNode.childNodes[0].className).toEqual("");
         expect(testNode.childNodes[0].getAttribute("class")).toEqual(null);
     });
-});
+});